Technical Field
The invention concerns a generator rotor for a generator, in particular a slowly rotating generator, of a wind turbine or a hydroelectric power plant. The invention further concerns a generator having such a generator rotor and a wind turbine having such a generator.
Description of the Related Art
Wind turbines are generally known. They have a tower on which a pod is rotatably mounted. Mounted on the pod, frequently in the interior thereof, are a machine carrier, a generator, a drive shaft for the generator, optionally a transmission, and a rotor hub having a number of rotor blades which rotate in the wind to drive the generator. The generator usually has a generator stator carried by the machine carrier and a generator rotor which rotates relative to the generator stator, preferably inwardly or outwardly thereof.
Hydroelectric power plants use turbines for generating electrical energy by means of the rotational drive of turbine blades, using the kinetic energy of a flow of water. In that respect a difference is basically made between turbines which by way of a rotor shaft transmit a torque into a region outside a flow passage, where then the torque at the rotor shaft is used to drive a generator, and those turbines in which the turbine rotors are connected directly to a rotor of a generator. The first-mentioned types are known inter alia from DE 10 2008 045 500 A1. In the latter case this is referred to as so-called straight-flow turbines. If the axis of rotation of the turbines is substantially parallel to the direction of flow of the water that is referred to as axial turbines. The generators which are used in the above-mentioned hydroelectric plants can be of a design which is substantially identical in function to the generators of wind turbines, and for that reason the invention also extends to that field.
The generator rotor has a plurality of pole shoes on a so-called rotor belt. The pole shoes rotate relative to the stator windings of the generator stator. Between the pole shoes and the windings of the generator stator there is an air gap which is as narrow as possible. A voltage is induced in the generator stator by way of an exciter field in the generator rotor. Torque fluctuations occur by virtue of the rotating exciter field which always behaves in a slightly unsteady fashion. Those torque fluctuations usually involve a frequency dependent on the speed of rotation of the generator rotor and cause vibrations in the generator.
The vibrations produced in the generator in that way are transmitted by way of the carrier structure and the hub flange to the main shaft of the wind turbine or component parts of the hydroelectric plant and in the first-mentioned case by way of same through the rotor hub into the rotor blades.
As wind turbines are increasingly also being erected in the proximity of populated areas particular attention is being paid to avoiding troublesome sound emissions to the greatest possible extent. In addition it is to be noted for known wind turbines that the construction of the carrier structure provided in the generator rotor is comparatively complicated and expensive. A multi-part steel structure is usually involved, which has to be manufactured in a correspondingly large number of working steps by means of welding and other joining technologies. The material and cost involvement is correspondingly high.
On the priority application in relation to the present application the German Patent and Trade Mark Office searched the following state of the art: DE 10 2008 045 500 A1, DE 10 2010 030 205 A1 and DE 10 2011 006 680 A1.